tetrabutyl ammonium fluoride in tetrahydrofuran T=20°C; 1 h;

1: xylene / 15 h / Heating 2: 83 percent / imidazole / dimethylformamide / 12 h / 25 °C 3: 81.7 percent / tetrahydrofuran / 6 h / 0 °C 4: 88 percent / BF3*OEt2; Et3SiH / CH2Cl2 5: 88 percent / Me2S*BH3 / tetrahydrofuran / 20 °C 6: 93 percent / TBAF / tetrahydrofuran / 1 h / 20 °C View Scheme

1: 83 percent / imidazole / dimethylformamide / 12 h / 25 °C 2: 81.7 percent / tetrahydrofuran / 6 h / 0 °C 3: 88 percent / BF3*OEt2; Et3SiH / CH2Cl2 4: 88 percent / Me2S*BH3 / tetrahydrofuran / 20 °C 5: 93 percent / TBAF / tetrahydrofuran / 1 h / 20 °C View Scheme

1: 88 percent / Me2S*BH3 / tetrahydrofuran / 20 °C 2: 93 percent / TBAF / tetrahydrofuran / 1 h / 20 °C View Scheme